AGE-SPECIFIC DEATH EATES OF MICE EXPOSED TO 

 IONIZING RADIATION AND RADIOMIMETIC AGENTS 



A. C. UPTON, M. A. KASTENBAUM, and J. W. CONKLIN 



Biology Division, Oak Ridge National Laboratory, 'f Oak Ridge, Tennessee, U.S.A. 



SUMMARY 



The life-shortening action of ionizing radiation in the mouse is well documented 

 (Mole, 1957; Neary, 1960; Upton, 1960). In this animal, moreover, irradiation early in 

 life causes a displacement of the Gompertz curve, which some observers say may indicate 

 induction of precocious senescence. As yet, however, there is relatively little detailed 

 information on the age-specific incidence of various diseases m the mouse, their relation 

 to senescence, and how their development is affected by radiation. Tliis report presents 

 preUminary results from a study of age-specific death rates of mice irradiated in earUer 

 experiments. 



METHODS 



The data reported herein were obtained from LAF^ mice exposed when 6 to 

 12 weeks old to y-rays from an experimental nuclear detonation (Upton et al., 

 1960); EF male mice exposed at 5 to 10 weeks of age to whole-body X-rays 

 (Upton et al., 1954; Upton, 1959; and unpublished data); and EF female 

 mice subjected at 10 weeks of age to mid-lethal doses of whole-body X-rays 

 (500-600 r), nitrogen mustard (HN2), 0-025-0-030 mg per kg, or triethylene 

 melamine (TEM), 3-0-4-0 mg/kg, (Upton et al, 1962). Unless otherwise 

 specified, the death rates for EF male mice were computed by the classical 

 actuarial method, and those for LAF^ mice by Seal's method, as described 

 earlier (Upton et al., 1960; Kimball, 1960). The data for EF female mice were 

 computed by a simpler actuarial procedure; i.e. the death rate was expressed 

 as the ratio between the number dying within an interval and the number alive 

 at the start of the interval, the length of the interval being determined by 

 percentage of the total population dying (10 or 20%) rather than by elapsed 

 time. In all cases, the data are based on animals dying naturally or killed in 

 extremis. 



RESULTS 



In both LAFj and EF mouse strains, the rate of over-aU mortality tended 

 to increase exponentially with tune beyond a certain age and was displaced 



t Operated by Union Carbide Corporation for the United States Atomic Energy 

 Commission. 



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